This invention relates to a fuel supply device and heating device and, more particularly, to a fuel supply device for an electronically controlled fuel injection system and a fuel heating device to be used therein.
In a conventional spark ignition internal combustion engine such as a gasoline engine, a carburetor is employed for sending a mixture of gasoline and air to a combustion chamber. The carburetor has the function of atomizing the gasoline by utilizing the vacuum or negative pressure inside the engine and making a combustible gas (mixed air and fuel) by automatically supplying a suitable quantity of air, as there is need for it. Accordingly, gasoline is only supplied as the vacuum or negative pressure requires, with the consequence that accelerator control of the engine is less responsive than would be desired.
Particularly in the case of a passenger automobile, it is necessary to supply a large quantity of gasoline to the combustion chamber to increase acceleration as soon as the accelerator is stepped on. In the case of a racing car, in particular, the responsiveness in this regard can determine victory or defeat.
In recent years, therefore, the use of a fuel injector in the place of a carburetor is becoming wide-spread. Since the fuel injector does not rely on the negative pressure inside the engine but atomizes and injects the gasoline in a positive manner and it can be installed in the neighborhood of the combustion chamber close to a cylinder opening, the aforementioned response to accelerator control is more satisfactory. An electronically controlled fuel injection system which controls the amount of gasoline injected by a computer has a particular advantage in that the supply of a mixed air and fuel is effected under the optimal conditions at all times.
However, in such conventional fuel injection systems, some difficulty is experienced when the engine is cold during engine start-up in that a part of the injected fuel contacts the wall of the engine passageways leading to the engine cylinders and condenses on the passageway walls with the result that the amount of gasoline, and therefore the ratio of air to gasoline, entering the engine cylinder is less than optimum at just the time when acceleration is desired. As a result, satisfactory acceleration of the engine is not achieved immediately after engine start-up and the advantage of the fuel injection system is diminished. Attempts have been made to heat the air and/or fuel being furnished to the noted cylinder inlet/passageways but such attempts have tended to increase air passage resistance in the passageways or to otherwise disrupt the balance of air fuel mixture furnished to the cylinder inlet openings making it impossible to achieve the optimum air fuel ratios during the engine start-up period.